If you see HTTPS in the address bar instead of HTTP then you are using an encrypted connection.

If my reply solves your problem, please click "Solved It" next to this reply when signed-in to the forum.

To give a more full answer:

The padlock only shows that there is a secure connection and doesn't guarantee that you are connected to the right server. So you might still be connected to the wrong server if you make a typo in the URL and someone has claimed that mistyped URL. The functionality of the padlock has been replaced by the Site Identity Button on the left end of the location (address) bar.

https://support.mozilla.com/en-US/kb/Site+Identity+Button

http://www.mozilla.com/en-US/firefox/security/identity/

This has actually existed since Firefox 3.0

If you still want a padlock icon also then install this Extension. https://addons.mozilla.org/en-US/firefox/addon/padlock-icon/

Thanks James, the additional information is most helpful.

Please click the Solved It button next to the answer that answered or solved your Firefox support issue, it appears when you are logged in, so this thread gets marked as Solved to help other users who may have this same problem.